Xu Qingwen, Zhang Yuxia, Xiong Xunhao, Huang Yan, Salisbury Jeffery L, Hu Jinghua, Ling Kun
Department of Biochemistry and Molecular Biology, and Division of Hypertension and Nephrology, Mayo Clinic, 200 First Street SW, Rochester, MN 55902, USA.
J Cell Sci. 2014 Mar 15;127(Pt 6):1293-305. doi: 10.1242/jcs.141465. Epub 2014 Jan 16.
Centriole biogenesis depends on the polo-like kinase (PLK4) and a small group of structural proteins. The spatiotemporal regulation of these proteins at pre-existing centrioles is essential to ensure that centriole duplication occurs once per cell cycle. Here, we report that phosphatidylinositol 4-phosphate 5-kinase type-1 gamma (PIP5K1C, hereafter referred to as PIPKIγ) plays an important role in centriole fidelity. PIPKIγ localized in a ring-like pattern in the intermediate pericentriolar materials around the proximal end of the centriole in G1, S and G2 phases, but not in M phase. This localization was dependent upon an association with centrosomal protein of 152 KDa (CEP152). Without detaining cells in S or M phase, the depletion of PIPKIγ led to centriole amplification in a manner that was dependent upon PLK4 and spindle assembly abnormal protein 6 homolog (SAS6). The expression of exogenous PIPKIγ reduced centriole amplification that occurred as a result of endogenous PIPKIγ depletion, hydroxyurea treatment or PLK4 overexpression, suggesting that PIPKIγ is likely to function at the PLK4 level to restrain centriole duplication. Importantly, we found that PIPKIγ bound to the cryptic polo-box domain of PLK4 and that this binding reduced the kinase activity of PLK4. Together, our findings suggest that PIPKIγ is a novel negative regulator of centriole duplication, which acts by modulating the homeostasis of PLK4 activity.
中心粒的生物发生依赖于polo样激酶(PLK4)和一小群结构蛋白。这些蛋白在已有的中心粒上的时空调节对于确保每个细胞周期仅发生一次中心粒复制至关重要。在此,我们报道1型磷脂酰肌醇4-磷酸5-激酶γ(PIP5K1C,以下简称PIPKIγ)在中心粒保真度方面发挥重要作用。在G1、S和G2期,PIPKIγ以环状模式定位于中心粒近端周围的中间中心粒外周物质中,但在M期则不然。这种定位依赖于与152 kDa的中心体蛋白(CEP152)的结合。在不将细胞阻滞于S期或M期的情况下,PIPKIγ的缺失以依赖于PLK4和纺锤体组装异常蛋白6同源物(SAS6)的方式导致中心粒扩增。外源性PIPKIγ的表达减少了由于内源性PIPKIγ缺失、羟基脲处理或PLK4过表达而发生的中心粒扩增,这表明PIPKIγ可能在PLK4水平发挥作用以抑制中心粒复制。重要的是,我们发现PIPKIγ与PLK4的隐蔽polo框结构域结合,并且这种结合降低了PLK4的激酶活性。总之,我们的研究结果表明PIPKIγ是中心粒复制的一种新型负调节因子,其通过调节PLK4活性的稳态发挥作用。